[detach8]

Just wanted to share that I just switched from the very well known JB4 piggyback to a BM3 direct flash (w/off the shelf 91 octane map) on my 2014 X3 sDrive20i (N20B20A EWG).

Summary: The difference is MASSIVE.

I had initially gotten the JB4 in October last year because the 20i engine (184hp/270Nm) is way underpowered for the heavy and tall (not aerodynamic) X3. The car felt like a dog to drive around town.

I have the EWG but I did not buy the JB4 EWG harness since it has no effect on the map I was running (Map 1/2). I ran Map 1 initially (+4 psi), then decided to run Map 2 (+6 psi) since the 20i pushes around 8 psi stock, and my N20B20A has the low compression piston (I think - I believe the high compression ones are N20B20B) which should do 8+6 = ~14 psi safely.

Even at Map1 (~12 psi) with RON95 gas the JB4 wasn't doing so well but I got some RON98 into the car it was smoother. The JB4 did provide some oomph at higher RPMs or throttle angles, the car was still sluggish around town, and I find that there is a ~1s lag before I feel the boost "kick in". I drive almost 90% in the city so it gets frustrating.

So after about 7 months of JB4, I'm not feeling any better about the car/engine to a point that almost made me switch to the new 2017 Volvo XC60 AWD T5 (2.0L IL4 246hp/350Nm) - which is quite a nice car TBH but it was not financially sensible.

I spent weeks looking at various tuning shops in town, did my research and read up on tuning options, and finally decided to give BM3 a go.

After the flash, I left my JB4 connected in Map 0 (JB4 disabled) so I can basically use the JB4 to read boost values via bluetooth.

Driving right out of the parking lot, I already felt a difference - the throttle was sharper. The moment I got on the road, the difference was even more apparent. The car pulls better, even at 1,500 rpms. I thought all these was maybe the effect of a adaptation reset after the flash, but a few days later the car still feels the same and pulls very well, and even better than I had experienced at WOT.

The readout from JB4 bluetooth matches my butt dyno: The turbo is making at least 2~3 psi of boost between 1,500-2,500 rpms on very light throttle. The actual boost vs. DME requested boost matches quickly, i.e. no lag.

Previously on the JB4, my turbo would make close to no boost (1 psi or less) at low RPMs unless I got into Sport mode or increased my throttle angle by a fair bit, but that also causes a transmission downshift - which is annoying.

Now with the BM3, if I gave the throttle a jab, boost jumps quickly to >10, and at speeds above, say 50-60kph, there is sufficient load on the engine at low rpms that boost gets to 16 psi very quickly and is maintained at that level. The result is a car that responds faster, pulls better, and also does not do that annoying automatic transmission downshift since I don't have to get so hard on the pedal all the time.

I've only had the BM3 for about a week, but I am already enjoying my massively improved ride.

Do share your experience with BM3, if any.

P.S. I have no relationship with the creators of BM3 or any of their resellers.